The present invention relates to a method of folding an air bag for a driver to be mounted on the steering of the automobile.
Referring now to FIGS. 23(A) and 23(B), an example of an air bag apparatus for a driver""s seat according to the related art will be described. FIG. 23(A) is a plan view of an air bag apparatus for a driver""s seat according to the related art, and FIG. 23(B) is a cross sectional view taken along line 23(B)xe2x80x9423(B) in FIG. 23(A), and FIG. 24 is a perspective view showing a modular cover viewed from the backside.
A retainer 110 comprises a flat plate portion 114 to which an air bag 112 is attached, and a module cover connecting portion 116 which is a strip extending from the edge of the flat plate portion 114 to the direction opposite to a driver. The air bag 112 in the folded state is covered with a module cover 118. The module cover 118 comprises a main plate 118A facing the driver and leg portions 118B extending from the side portion of the main plate in the direction opposite to the driver. The leg portions 118B are secured to the module cover connecting portion 116 of the retainer 110 by rivets 120 or the like. The reference numeral 122 designates a reinforcing plate.
An inflator 124 is secured to the retainer 110 in such a manner that the upper side thereof is accommodated in the air bag 112 through an opening 126 formed on the flat plate portion 114. A ring 128 is an air bag connecting member. The opened edge of the air bag 112 is sandwiched between the ring 128 and the opened edge portion of the flat plate portion 114, so that the air bag 112 is secured to the retainer 110. Bolts, not shown, which are fixed to the ring 128, are inserted into bolt insertion holes formed at the opened edge of the air bag 112, the flat plate portion 114 of the retainer, and a flange 124a of the inflator 124, and nuts are tightened onto the bolts.
The back surface of the main plate 118A of the module cover 118 has tear lines 130, 132, 134 of shallow grooves formed as weakened portion for ripping the main plate 118A. The tear lines 130, 132 extend along the leg portions 118B on the left side and the right side in FIG. 23(A) in the vertical direction of FIG. 23(A). The tear line 134 extends laterally of FIG. 23(A) at about the center of the main plate 118A so as to connect the tear lines 130 and 132 together.
The main plate 118A of the module cover surrounded by these tear lines 130, 132 and 134 are divided into two sections, i.e. flaps 140 and 142. When the inflator 124 is operated to blow gas to inflate the air bag 112, the portions of the module cover 118 along the tear lines 130, 132 and 134 are torn or ripped, so that the flaps 140, 142 can be outwardly opened respectively into a tongue shape.
When the inflator 124 operates in association with the collision of the vehicle, a large amount of gas is rapidly blown out from the inflator 124 and the air bag 112 starts to inflate. Then, the module cover 118 is ripped along the tear lines 130, 132 and 134 in association with the inflation of the air bag 112, and the flaps 140 and 142 are respectively opened into a tongue shape, so that the air bag 112 is rapidly inflated in the compartment of the vehicle to protect the driver therein.
Though the air bag apparatus for a driver""s seat comprises three spoke portions 151, 152 and 153, an air bag apparatus for a driver""s seat having two or four spoke portions is also widely used.
FIG. 25 is a perspective view of a steering wheel 165 having an air bag apparatus for a driver""s seat 160 having four spoke portions 161, 162, 163 and 164. There is also provided a tear line 167 on a module cover 166 of the air bag apparatus for a driver""s seat 160.
The module cover 118 or 166 of the above described related air bag apparatus for a driver""s seat comprises a center portion and spoke portions extending from the center portion radially outwardly, and the air bag is covered only with the center portion.
In this way, in the air bag apparatus for the driver""s seat covered only with the center portion of the module cover 118 or 166, the module cover and the air bag apparatus are significantly large because they have to cover the air bag.
Accordingly, in view of the above problem of the related art, the object of the present invention is to provide an air bag apparatus for a driver""s seat having relatively small and slim appearance.
In a method of folding an air bag for a driver, an air bag is placed in a flat form to orient an upper surface of the air bag upwardly, and then, at least two side areas of the air bag in the flat form are folded inwardly of the air bag so that at least two arm portions extending radially outwardly from a center portion of the air bag to lateral portions on an outer periphery of the air bag are formed without being folded toward the center of the air bag. The arm portions have elongated shapes extending along spokes of a steering wheel.
Each of the at least two side areas of the air bag is placed at the center portion and at least two arm portions. Preferably, each of the at least two side areas is folded in bellows so that folded portions in a form of bellows extend between the lateral portions through the center portion.
The folded air bag may have three or more arm portions extending from the center portion according to the number of the spokes of the steering wheel.
In the method of the invention, at least three side areas of the air bag in the flat form may be pushed toward the center portion to form at least three petal-shaped portions extending radially outwardly from the center portion, and side portions of each petal-shaped portion are rolled inwardly to form the arm portion. On the other hand, each of the upper and lower sides of the air bag in the flat form may be folded in bellows and disposed on a middle area between the upper and lower sides without overlapping each other to form an elongated form. Also, each of upper and lower sides of the air bag in the flat form may be rolled inwardly toward a center area without overlapping each other.
In the method of the invention, the air bag can be folded from the center to the spokes of the steering wheel. Thus, the center of the steering wheel can be made relatively compact.